12 W high power InGaAsP/AlGaInP 755 nm quantum well laser

High power laser diodes(LDs) with a lasing wavelength between 700 and 780 nm have great potential in various medical uses. Here, we report our recent efforts in developing an InGaAsP/AlGaInP-based commercial high power edge-emitting LD, which has 755 nm emission peak with a world-record continuous wave output power of 12.7 W, the highest reported so far. The lack of Al atoms in the active region significantly lowers the chance of catastrophic optical damage during high power laser operation. Meanwhile, with an accumulated 3800 h running time, our ongoing aging tests reveal excellent reliability of our devices.     

Detecting molecular vibrational modes of side chains and endpoints in nanoscale proteins with graphene plasmon

Monitoring the chemical and structural changes in protein side chains and endpoints by infrared(IR)spectroscopy is important for studying the chemical reaction and physical adsorption process of proteins.However, the detection of side chains and endpoints in nanoscale proteins is still challenging due to its weak IR response. Here, by designing a double layered graphene plasmon sensor on MgF_2/Si substrate in the IR fingerprint region, we detect the vibrational modes in side chains and endpoints(1397 cm~(-1) and 1458 cm~(-1)) of monolayer protein. The sensor could be applied on biochemistry to investigate the physical and chemical reaction of biomolecules.     

Ultra-compact graphene plasmonic filter integrated in a waveguide

Graphene plasmons have become promising candidates for deep-subwavelength nanoscale optical devices due to their strong field confinement and low damping. Among these nanoscale optical devices, band-pass filter for wavelength selection and noise filtering are key devices in an integrated optical circuit. However, plasmonic filters are still oversized because large resonant cavities are needed to perform frequency selection. Here, an ultra-compact filter integrated in a graphene plasmonic waveguide was designed, where a rectangular resonant cavity is inside a graphene nanoribbon waveguide. The properties of the filter were studied using the finite-difference time-domain method and demonstrated using the analytical model. The results demonstrate the band-pass filter has a high quality factor(20.36) and electrically tunable frequency response. The working frequency of the filter could also be tuned by modifying the cavity size. Our work provides a feasible structure for a graphene plasmonic nano-filter for future use in integrated optical circuits.     

单分子光谱检测法的新进展

自上世纪90年代以来，单分子检测已经取得了巨大的进步。它提供了大量非平衡体系中个体或平衡态脉动体系的信息，而这些信息是无法从传统的统计测量中获得的。本文主要介绍近10年来，单分子光谱检测技术从低温到室温、从非溶液介质到水溶液、从固体到活细胞、从有机染料分子到纳米粒子等方面的进展情况。     

用水溶液中合成的量子点作为生物荧光标记物的研究

以巯基丙酸(HS—CH2CH2COOH)为稳定剂,在水溶液中合成了具有窄而对称(FWHM=40nm)的荧光发射带且尺寸为3nm的CdTe半导体纳米粒子,并用此纳米粒子成功地标记了生物分子胰蛋白酶.与单独的CdTe纳米粒子的溶液相比较,CdTe-胰蛋白酶溶液的吸收光谱在400～600nm范围内较为平坦,其发射光谱蓝移8nm,但发射峰的半峰宽不变.实验证明,CdTe-胰蛋白酶溶液吸收和发射光谱的变化是由CdTe纳米粒子与胰蛋白酶之间的结合反应引起的,而不是由空气中的O2所引起的,加热可促进CdTe纳米粒子与胰蛋白酶之间的结合反应.     

石墨烯等离激元增强红外光谱

红外光谱能够精准反映分子振动的信息,是表征材料成分和结构的重要手段.但是纳米尺度材料与微米尺度红外光波长之间约三个数量级的尺寸失配导致两者之间相互作用十分微弱,无法直接进行红外光谱表征.因此如何获得微量纳米材料的红外光谱信息成为了近年来红外光谱领域面临的关键挑战.等离激元能够将光场压缩实现局域光场增强,从而增强光与物质的相互作用.其中石墨烯等离激元因其具有高光场压缩、电学动态可调和低本征衰减等优点,为表面增强红外光谱提供了重要的解决方案.本文首先从不同材料体系出发介绍了红外等离激元,在此基础上从石墨烯的基本性质出发总结石墨烯等离激元及其在表面增强红外光谱上的优势,并重点介绍了石墨烯等离激元增强红外光谱的最新进展和应用,包括单分子层生物化学探测、气体识别和折射率传感等.最后对石墨烯等离激元增强红外光谱的下一步发展方向和应用前景进行了展望.     

12 W高功率高可靠性915 nm半导体激光器设计与制作

本文设计并制作了一种高效率、高可靠性的915 nm半导体激光器。半导体激光器是光纤激光器的关键部件,为了最大限度地提高器件的电光转换效率,在设计上采用双非对称大光腔波导结构,同时对量子阱结构、波导结构、掺杂以及器件结构进行了系统优化。器件模拟表明,在25℃环境温度下,器件的最高电光转换效率达到67%。采用金属有机气相沉积(MOCVD)法进行材料生长,随后制备了发光区域宽度为95μm、腔长为4.8 mm的激光芯片。测试表明,封装后器件的效率以及其它参数指标达到国际先进水平,在室温下阈值电流为1 A,斜率效率为1.18 W/A,最高电光转换效率达66.5%,输出功率12 W时,电光转换效率达到64.3%,测试结果与器件理论模拟高度吻合。经过约6 000 h的寿命加速测试,器件功率没有出现衰减,表明制作的高功率915 nm激光芯片具有很高的可靠性。     

三维编织复合材料圆柱壳的扭转后屈曲分析

随着三维编织复合材料应用的日益广泛,且由于三维编织复合材料的优异性能是与细观结构密切相关的,深入研究其细观结构显得尤为重要.本文通过研究三维圆型编织中所形成的空间纱线交织结构的特征,给出改进的三胞结构单胞模型,通过单胞的组装和变换,得到编织预制件的整体力学性能模型.基于Reddy高阶剪切变形理论导得广义Krmn型大挠度方程,计及边界层效应,采用奇异摄动法,考虑非线性前屈曲、大挠度和初始几何缺陷的影响,给出三维四向编织复合材料圆柱壳在扭转载荷作用下的严格满足边界条件的大挠度渐近解,讨论了纤维体积含量、编织角和几何参数等因素对圆柱壳屈曲和后屈曲行为的影响.